• 한국항행학회논문지
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• 제27권5호
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• pp.621-628
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• 2023

본 연구는 항공기용 부품 및 장비품 중 치명성 부품인 수송류 항공기용 금속계 제동패드의 부품등제작자증명 및 부가형식증명을 위한 원 부품 등과 개발품의 설계 동일성 입증을 위한 역설계 절차를 도출하였다. 역설계 절차에 대한 규정은 우리나라의 경우 부품등제작자증명 지침에 의해 규정되며, 미국의 경우 AC No; 21.303-4에 규정되어 있다. 제동패드의 역설계 절차는 각 구성품별 샘플 수량, 치수공차, 기계적 물성 측정, 자재, 무게 및 부피특성 등의 동일성 확인 항목을 선정하여 각각의 세부 절차를 정의하였다. 아울러 우리나라 및 미국의 연방항공규정을 분석한 결과, 우리나라의 경우 수송류 항공기용 제동장치의 기술표준품 표준서 및 비행시험과 관련된 규정의 제정이 필요하다.

• 한국항행학회논문지
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• 제3권2호
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• pp.97-107
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• 1999

항공기의 착륙을 추적하기 위해 많이 사용되는 수동 센서인 레이저 거리 측정기(LRF)와 전방관측 적외선 카메라(FLIR)는 배기가스교란(Exhaust Plume Disturbance)으로 인한 고도각 측정 시에 오차를 발생시킨다. 이 경우에 확장형 칼만필터(EKF)를 사용하여 거리 및 고도를 측정하면 배기가스(plume)와 같은 비-가우시안 잡음 때문에 추적 성능이 저하된다. 본 논문에서는 배기가스의 발생 타이밍을 검출기(PD)를 사용하여 확인한 후에 배기가스가 발생하면 적응형 추산법을 사용하고 배기가스의 영향이 없을 때에는 기존의 확장형 칼만필터를 사용하는 복합 방식을 제안하고 이를 위한 적응형 필터를 설계한다. 이 혼합형 필터는 배기가스와 같은 미지의 바이어스를 제거하는데 매우 효과적인 방법이며 시뮬레이션을 통하여 이러한 성능을 예증한다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.212-215
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• 2002

Interfacial evaluation and damage sensing of the carbon fiber/epoxy-amine terminated (AT)-polyetherimide (PEI) composites were performed using micromechanical test and electrical resistance measurement. As AT-PEI content increased, the fracture toughness of epoxy-AT-PEI matrix increased, and thus their interfacial shear strength (IFSS) was improved due to the improved toughness. After curing process, the changes in electrical resistance (ΔR) with increasing AT-PEI contents increased gradually because of the changes in thermal expansion coefficient (TEC) and thermal shrinkage of matrix. Matrix fracture toughness was correlated to the IFSS, residual stress and electrical resistance. The results obtained from the electrical resistance measurement during curing process, reversible stress/strain, and durability test were consistent with modified matrix toughness properties.

• 대기
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• 제20권4호
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• pp.427-436
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• 2010

The single-scattering optical properties of ice crystals in cirrus clouds by the aircraft measurement data were investigated, and the radiative equilibrium temperatures and radiative fluxes were calculated and analyzed by radiative convective model with the variations of ice crystal habits and sizes in cirrus clouds. The homogeneous cloud is assumed to be in the layer 200~260 hPa with an ice crystal content of $10gm^{-2}$ for the flux calculation. The profiles of temperature, humidity, and ozone typical of mid-latitude summer are used. The surface albedo is assumed to be 0.2 for all spectral bands and the cosine of solar zenith angles is 0.5. The result of radiative equilibrium temperature at surface was less than surface temperature of the standard atmosphere data in case of smaller effective ice crystal size and larger optical thickness. The column, aggregation and plate in 6 ice crystal habits were the most effective in positive greenhouse effect and bullet-4 was the worst in it. At the surface, the maximum difference of equilibrium temperature by 6 kinds of ice crystal habits were about 3~15 K with 30 sample aircraft measurement data.

• 비파괴검사학회지
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• 제21권2호
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• pp.177-181
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• 2001

광학적 비접촉 비파괴검사 방법인 ESPI, Shearography를 이용한 측정은 자동차나 항공기산업 등에서 최근 폭넓게 이용되고 있다. 빠른 측정 속도와 측정 대상의 전 영역을 한번에 측정할 수 있는 장점을 가진 Shearography를 이용한 비파괴검사 방법을 기존의 광계측법인 ESPI와 비교하였다. 또한 이러한 장점을 살려 산업현장에서 수행한 여러 가지 비파괴검사 사례를 제시하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2532-2537
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• 2005

FIR(Finite Impulse Response) filter is well known to be ideal for the finite time state-space model, but it requires much computation due to its inherent non-recursive structure especially when the measurement interval grows to a large extent. And often a fixed-lag smoother based on the finite time interval is needed to monitor the soundness of the system model and the measurement model, but the computation burden of FIR-type smoother imposes much restriction of its usage for real-time application. Conventional recursive forms of FIR estimator[1]-[4] could not be used for real time applications, since they are numerically unstable in their recursive equations. To cope with this problem, we suggest a stable recursive form FIR estimator(SRFIR) and its usefulness is demonstrated for designing the real-time fixed-lag smoother on the finite time window through an example of detection of rate bias in the anti-aircraft gun fire control system.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제4권1호
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• pp.10-21
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• 2001

A new method of laser remote sensing is proposed, based on sensing the sea surface by a narrow laser beam (2-3cm) and analyzing statistically specular reflections. Construction of the angular dependency of the average density of specks versus the aircraft flight horizontal azimuth allows calculation of both intensity and azimuthal properties of the sea surface spectrum. The paper contains the experimental setup and technique, the field measurement data taken onboard an aircraft and the examples of calculated main statistical parameters of sea waves. Their energy-carrying component velocity is found by the mean velocity of an ensemble of specular points at the random sea surface. The surface wave nonlinearity is shown to affect substantially the statistical characteristics measured: mean numbers of specular areas with th given elevation and given slope, arranged along the line of crossing the sea surface by the scanning laser beam. Experimental measurement of a variance in the number of these areas yields a principal possibility to calculate the correlation function of the sea surface without its preliminary modeling.

• 한국대기환경학회지
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• 제15권6호
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• pp.713-725
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• 1999

Air pollutants($SO_2$, NOx, $O_3$ and aerosol number) were measured using an aircraft to investigate the characteristical features of long-range transport of sulfur compounds over the Yellow Sea for the periods of 26~27 April and 7~10 November in 1998. The mean $SO_2$ concentrations of April 26th~27th and November 7th~10th flight were 0.6~1.8 ppb and 0.5~8.3 ppb, respectively, and the sulfur transport was largely limited to the atmospheric boundary layer. Especially, $SO_2$ increased up to 8.3 ppb altogether with the increase of particle number concentraton especially on November 8, 1998. In addition, $O_3$ was remarkably decreased against the increase of $SO_2$and particle number concentrations. This enhanced $SO_2$ concentration occurred in the low level westerlies in association with the anticyclonic flow over Southern China and the cyclonic circulation over Manchuria. Aerosol analyses at Taean site also showed that sulfate concentration increased 2~3 times higher than those of another sampling days, which could suggest possible interactions between aerosol particels and tropospheric ozone. A rigorous evaluation will be possible after the more intensive measurements and quantitative analyses with detailed chemistry model including the postulated heterogeneous mechanism.

• 대한기계학회논문집B
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• 제36권12호
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• pp.1217-1222
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• 2012

능동 유동 제어의 되먹임 신호 및 벽면 전단 응력 측정 등을 위해 벽면 유동 센서가 사용되고 있다. 본 연구에서는 광학 마우스에 사용되는 미세 영상 장치를 이용하여 벽면 근처에서 2차원 및 3차원 유체 속도를 측정할 수 있는 센서를 개발하였다. 미세 영상 장치에서 나오는 영상 신호 획득 시스템을 구축하고 획득한 영상에 입자화상속도기법과 초점이탈 영상기법을 적용하여 측정 영역에서의 산란 입자의 위치를 측정하였다. 모사 유동 실험을 통해, 개발된 벽면 유동 센서의 공간 해상도 및 측정 정확도를 검증하였고 기존 미세 영상 장치의 quadrature 신호 결과와 비교하여 입자화상속도기법을 적용할 경우, 측정 정확도 및 측정 범위가 확대되는 것을 확인하였다.

• 항공우주시스템공학회지
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• 제14권6호
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• pp.91-99
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• 2020

This study proposes a finite element (FE) model for predicting the bending strength of small gears used in electro-mechanical actuators for aircraft. First, a strain gauge was attached to the tooth root of test gear, and the strain was measured. Subsequently, the FE model was applied to calculate the strain of the test gear, and the modeled strain was compared with the experimental strain. The results confirmed that the FE strain was very close to the experimental strain and the FE model was valid. This FE model was extended to the bending strength analysis of several small gear tooth models. The bending strengths of all the tooth models were almost identical to the ISO theoretical bending strength. Finally, the FE model was validated and the reliability of the modeled bending strength was evaluated through the strain measurement experiment.